1. Technical Field
The present application relates to a drill bit for drilling having at least two cutting edges, each with two cutting portions and a non-cutting portion between the two cutting portions. The present application further relates to a bit for a drill tool extending along a drill center axis in the drill longitudinal direction and having an outwardly extending cutting edge.
2. Background Information
Background information is for informational purposes only and does not necessarily admit that subsequently mentioned information and publications are prior art.
In some drills, the bit is clamped in an end-side groove of a drill body. The cutting edge of the bit runs in a substantially S-shaped manner from a drill center outward to a drill circumference. In the drill longitudinal direction, a chip groove wall of a coiled chip groove adjoins the cutting edge. The chips which are removed during machining via the cutting edge are discharged via the chip groove.
In order to essentially ensure or promote a continuous drilling process which is as trouble-free as possible the chips must or should be discharged reliably and safely via the chip groove. The chip must or should have a suitable shape for this purpose. Thus, the problem often occurs that the machining process leads to the formation of chips which are embodied in a substantially helical manner and some of which take up more free space than the free space provided by the chip groove. This may lead to the chips becoming stuck within the chip groove, so that discharge is no longer reliably essentially ensured or promoted. There is also the risk of chips passing between the drill circumference and the drill wall and becoming stuck there; this leads to damage to the drill wall and to imprecise drill hole geometry and also to greatly increased stressing of the drill tool.
The problem of sufficiently safe removal of chips is encountered for example in long-chipping materials, such as for example high-grade stainless steel, in which very long chips are formed during the machining process.
The use of what are known as chip breakers is known to avoid, restrict, and/or minimize excessively large chips. Thus, some plate-shaped cutting inserts for drill tools have chip breakers which are formed by transverse grooves perpendicularly or virtually perpendicularly to the cutting edge. The cutting edge is in this case therefore interrupted at the positions of the chip breakers.